Mario Draghi's efforts to kickstart European growth are also hitting the region's investment banks where it hurts.

The European Central Bank chief's ramped-up program of quantitative easing, announced last week, expands monthly bond purchases from 60 billion euros ($68 billion) to 80 billion euros. It also extends the purchases from mostly government bonds to non-bank investment grade company bonds.

The jury is out on whether this will have the desired effect of boosting activity in the region's sickly economy. But one dead cert is that investment bank trading desks for fixed income, commodities and currencies will suffer.

Share of investment banks' revenues from FICC trading

43%

The ECB's QE program -- which has already taken a significant chunk of the region's government-debt market off the table -- now promises to do the same to the corporate bond market too.

Bernstein Research analyst Chirantan Barua estimates that average monthly liquidity in euro area non-bank, investment-grade debt is between 25 billion euros and 35 billion euros. Assuming up to 10 billion euros of the expanded purchase program goes toward this kind of debt, the ECB could plausibly soak up about 30 percent of liquidity.

Trading Down

FICC revenues at the biggest global investment banks are in steady decline

Source: Bernstein, based on analysis of 13 global banks

* Bernstein estimates

That puts further strain on FICC trading desks, where revenues have declined steadily since the financial crisis, partly because of regulation that has made the division more capital intensive and less profitable. Across major global firms, the proportion of investment banking revenue from FICC trading fell from 61 percent in 2009 to 43 percent in 2015, HSBC estimates.

In theory, QE -- in the U.S. and Japan as well as Europe -- could bolster other sources of revenue, supporting dealmaking and boosting equities businesses. And, the banks could also benefit from renewed economic growth. But that's of little comfort to those firms still most exposed to FICC. At Deutsche Bank, the desks still account for 57 percent of total investment bank revenues, HSBC notes.

Fixed Income

Deutsche Bank earns a bigger share of its investment banking revenue from FICC than its rivals

Bank chiefs are already tackling the decline in FICC revenues, and many have already pledged to scale back their trading businesses. But the sharper drop-off would make broader restructuring of their firms all the harder. Cost-cutting targets would struggle to keep pace with revenue that's falling faster than previously anticipated, while the competition intensifies over an ever-shrinking pool of other businesses.

The outcome of Draghi's big move to revive European growth remains to be seen. From one perspective, though, he's heaped yet more misery on the region's investment banks.

This column does not necessarily reflect the opinion of Bloomberg LP and its owners.